Spatially selective heating of intermediate transfer member

Abstract

In an example, an apparatus is described that includes a photosensitive imaging plate, an intermediate transfer member, and a heating unit. The photosensitive imaging plate attracts a layer of printing fluid. The intermediate transfer member contacts the photosensitive imaging plate and receives the layer of printing fluid from the photosensitive imaging plate. The heating unit includes an array of individually addressable heating elements and heats the intermediate transfer member in a manner that is spatially selective along two axes; a first axis in a direction of a width of the intermediate transfer member and a second axis in a direction of a rotation of the intermediate transfer member.

What is claimed is: 
     
       1. An apparatus, comprising:
 a photosensitive imaging plate (PIP) for attracting a layer of printing fluid; 
 a charge roller positioned in proximity to the PIP to project a uniform electrostatic charge onto a surface of the PIP as the PIP rotates; 
 a laser unit positioned in proximity to the PIP and after the charge roller to selectively remove electrostatic charge on the surface of the PIP to form an image as the PIP rotates; 
 a plurality of developers positioned in proximity to the PIP after the laser unit to dispense the layer of printing fluid onto the surface of the PIP having an electrostatic charge as the PIP rotates; 
 an intermediate transfer member (ITM) contacting the PIP, for receiving the layer of printing fluid from the PIP as the ITM rotates in a direction that is opposite a direction of rotation of the PIP; 
 a heating unit positioned in proximity to the ITM and opposite the PIP, wherein the heating unit comprises an array of individually addressable heating elements for heating the ITM in a manner that is spatially selective along a first axis in a direction of a width of the ITM and along a second axis in a direction of a rotation of the ITM; 
 an impression press positioned in proximity to the ITM that rotates in a direction that is opposite the direction of rotation of the ITM and transfers the image onto a substrate that passes through between the ITM and the impression press; and 
 a controller to control operation of the laser unit, the plurality of developers, and each one of the individually addressable heating elements of the array, wherein the controller is to identify areas on the ITM that are free from the layer of printing fluid based on a mapping created by a raster image processor and to generate a signal to not activate a subset of the individually addressable heating elements that correspond to the areas on the ITM that are free from the layer of printing fluid. 
 
     
     
       2. The apparatus of  claim 1 , wherein each of the individually addressable heating elements comprises a laser emitter. 
     
     
       3. The apparatus of  claim 2 , wherein each of the individually addressable heating elements comprises a vertical cavity surface-emitting laser emitter. 
     
     
       4. The apparatus of  claim 1 , wherein the array comprises at least one row and a plurality of columns, and each of the individually addressable heating elements is positioned at an intersection of one of the at least one row and one of the plurality of columns. 
     
     
       5. The apparatus of  claim 4 , wherein each of the at least one row and each of the plurality of columns is connected to a controller that sends signals to the individually addressable heating elements. 
     
     
       6. The apparatus of  claim 1 , wherein the layer of printing fluid comprises a layer of liquid electrophotographic ink. 
     
     
       7. A method, comprising:
 projecting a uniform electrostatic charge onto a surface of a photosensitive imaging plate (PIP) via a charge roller in proximity to the PIP as the PIP rotates; 
 selectively removing electrostatic charge on the surface of the PIP to form an image via a laser unit positioned in proximity to the PIP as the PIP rotates; 
 transferring a layer of printing fluid onto the surface of the PIP having an electrostatic charge via a plurality of developers positioned in proximity to the PIP as the PIP rotates; 
 transferring the layer of printing fluid to an intermediate transfer member (ITM) that rotates in a direction that is opposite a direction of rotation of the PIP; 
 identifying areas of the ITM that are free from the layer of printing fluid based on a mapping created by a raster image processor; 
 subsequent to transferring the layer of printing fluid to the ITM, generating a signal to not activate a subset of individually addressable heating elements of an array of individually addressable heating elements that correspond to the areas of the ITM that are free from the layer of printing fluid, while heating the ITM in a manner that is spatially selective along a first axis in a direction of a width of the ITM and along a second axis in a direction of a rotation of the ITM; and 
 subsequent to heating the ITM, transferring the layer of printing fluid from the ITM to a substrate that is passed between an impression press and the ITM, wherein the impression press is positioned in proximity to the ITM and rotates in a direction that is opposite the direction of rotation of the ITM. 
 
     
     
       8. The method of  claim 7 , wherein the printing fluid comprises liquid electrophotographic ink. 
     
     
       9. The method of  claim 7 , wherein the heating comprises:
 applying heat from at least one heating element in an array of individually addressable heating elements. 
 
     
     
       10. The method of  claim 9 , wherein each of the individually addressable heating elements comprises a laser emitter. 
     
     
       11. The method of  claim 10 , wherein each of the individually addressable heating elements comprises a vertical cavity surface-emitting laser emitter. 
     
     
       12. The method of  claim 9 , wherein the array comprises at least one row and a plurality of columns, and each of the individually addressable heating elements is positioned at an intersection of one of the at least one row and one of the plurality of columns. 
     
     
       13. The method of  claim 7 , wherein the heating results in direct heat being applied to less than an entirety of the ITM. 
     
     
       14. A non-transitory machine-readable storage medium encoded with instructions executable by a processor, the machine-readable storage medium comprising:
 instructions to project a uniform electrostatic charge onto a surface of a photosensitive imaging plate (PIP) via a charge roller in proximity to the PIP as the PIP rotates; 
 instructions to identify an area of a photosensitive imaging plate (PIP) that will receive a layer of printing fluid; 
 instructions to selectively remove charge on a surface of the PIP except for portions of the surface that will receive the layer of printing fluid as the PIP rotates; 
 instructions to transfer the layer of printing fluid onto the surface of the PIP having an electrostatic charge via a plurality of developers positioned in proximity to the PIP as the PIP rotates; 
 instructions to transfer the layer of printing fluid to an intermediate transfer member (ITM) that rotates in a direction that is opposite a direction of rotation of the PIP; 
 instructions to identify areas of the ITM that are free from the layer of printing fluid based on a mapping created by a raster image processor; 
 instructions to, subsequent to the instructions to transfer the layer of printing fluid to the ITM, generate a signal to not activate a subset of individually addressable heating elements of an array of individually addressable heating elements that correspond to the areas of the ITM that are free from the layer of printing fluid, while heating the ITM using remaining individually addressable heating elements of the array of individually addressable heating elements, wherein the array is arranged to provide heat in a manner that is spatially selective along a first axis in a direction of a width of the ITM and along a second axis in a direction of a rotation of the ITM; and 
 instructions to transfer the layer of printing fluid from the ITM to a substrate that is passed between an impression press and the ITM, wherein the impression press is positioned in proximity to the ITM and rotates in a direction that is opposite the direction of rotation of the ITM. 
 
     
     
       15. The non-transitory machine-readable storage medium of  claim 14 , wherein the instructions to heat result in direct heat being applied to less than an entirety of the ITM.